Project Raijin

Community-owned, sustainable, scalable tools on unstructured climate and global weather data


The Xarray package extends the capabilities of NumPy arrays by introducing labeled dimensions, coordinates, and attributes, as well as the ability to read data from a number of scientific file formats such as netCDF. Xarray was designed with regular gridded data in mind and does not recognize unstructured grids, treating them simply as one-dimensional arrays of points.

We are creating a new Python object based on Xarray, called UXarray, which will support reading and recognizing unstructured grid models. Initially, we will support: MPAS (atmosphere and ocean), SE, FV3, and ICON. UXarray will follow the model of the UGRID specification, currently under consideration to be included in the netCDF CF conventions, as well as support SCRIP, Exodus, and shapefile formats for the internal representation of auxiliary data needed to describe an unstructured mesh (e.g. cell types and cell connectivity information).

We note that basing UXarray on Xarray will facilitate interoperability with the multitude of Xarray-compatible packages, a priority for our work.

Open development and community engagement

The UXarray effort is a result of the collaboration between Project Raijin and DOE’s SEATS Project (Argonne National Laboratory, UC Davis, and Lawrence Livermore National Laboratory). The Uxarray team welcomes other community members to become part of this collaboration at any level of contribution. To read further documentation, work with the code, start a discussion, make a request, or report an issue, please visit:

UXarray Github repository

UXarray documentation

Lastly, in anticipation that community members will want to add support for other unstructured grid models outside the scope of this proposal, including global and regional ocean models such as FVCOM, our project’s Contributor’s guide will provide a detailed description of this particular topic.

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